Imaging devices, such as an X-ray device or a tomographic device enable the recording of images of a region under examination at different times. A comparison of the images enables information with a temporal component to be derived from these images. The images generally represent a volume and can include a plurality of prespecifiable slices of the region under examination. If a substance flows through the region under examination, it is also possible to derive flow information from the images. Thus, modern imaging devices enable the identification of disorders of the blood flow in organs, for example the heart or the brain. The most important methods for imaging measurements of the blood flow include angiography and tomography perfusion scanning.
Therefore, the evaluation of the images requires the evaluation of both anatomical information and flow information. Anatomical information relates to the anatomical structure of the region under examination and hence has a spatial component. Flow information relates to the dynamics of a substance flowing in the region under examination and hence has both a spatial and a temporal component. The depiction of spatial and temporal information for an imaging measurement is typically performed in that an image stack with a plurality of slices is compiled for each time point. The spatial and temporal information can then be depicted in that individual slices or projections of the image stack are output as a temporally sequential sequence. Hence, this enables the evaluation of the temporal development of a substance flowing in the region under examination. However, this is time-consuming and above all disadvantageous for documentation.
To simplify the processing of spatial and temporal information, the U.S. Pat. No. 6,650,928 B1 suggests the conversion of tomographic images into color-coded maps. For example, two images of brain structures are overlaid. This involves the overlaying of a colored, parametric image over an anatomical image. The transparency of the overlaid image is adjustable to allow more or less of the anatomical structure to be seen. The drawback of this method is that good visibility of the anatomical information impairs the visibility of the parametric information.